EFIDynoTuning Forum

I'm having trouble diagnosing a datalog and my engine missing at roughly 4800rpm.

• At high RPM (WOT and CL) the engine stops making power at 4800rpm and falls to around 4000rpm before building to 4800rpm and repeating the cycle.

• At these specific times the datalog column of "FUEL_IN_SYNC" stops reading "sequential fire" and is blank for a few sample Counts

• Datalog column FUELPW1 also increases by a factor of three occasionally when this issues happens

Any suggestions on what to look at? Is it tune related? I swapped out the distributor today (different TFI and pip) and had similar results. Car is also supercharged.

yep your hitting the 2 step.

I inverted the clutch input to the 2 step.

btw your doing an excellent job dialing in the maf, keep it up.

UPDATE UPDATE UPDATE - Problem Fixed

Let this be a lesson to anyone who has been copy and pasting their tunes on each A9L2 update over the years. I think my base tune is from a 2016 version of A9L2 and I've been casually copying and pasting my tune until now when updates are released. It finally bit me when I did a deep dive on the latest A9L2 to look at what was different and If I had missed something or accidently setup anything wrong.

Turns out on a few of my latest tunes the "Perload Switch - PRLDSW" was incorrectly checked/selected. I'm not sure when I accidently checked it, but when the car hit boost and load = 100% bad things were starting to happen, now that load is being correctly calculated as load/peak load the car runs great.

edit: i also found that the two step RPM was set at 4875 and raised it to the latest values i saw in the current A9L2.